1. Field of the Invention
This invention lies in the field of badge and document reading devices and, more particularly, manually operable badge readers.
2. Description of the Prior Art
The rapidly expanding data processing technology has forced development of many new modes of data collection. One such mode that is currently increasing and has a large potential for industrial application is that of collecting data from badges or the like which are carried by individuals. In many industrial systems, activity records and other events are monitored by having individuals at predetermined locations insert badges into readers, which badges are designed to be encoded so as to permit reliable data recognition. The types of such badges are standardized, and for many of the badges in use it is either impractical or undesirable to have a motorized transport system within the reader. For this reason, the prevalent arrangement is to have the person who carries the badge insert it manually and withdraw it manually from the reader, during which time the reader must perform the reading operation.
One possible method of triggering the reader to read the encoded data as the badge is entered or withdrawn, is to place synchronizing or clock marks on the badge or document itself. Thus, it is a standard practice in the art of document reading generally to have clock signals printed along a side or a particular column of a document, which signals are detected as they pass by a sensor, thereby giving rise to clock signals which in turn are used to control reading of encoded data. One problem with this arrangement is that it substantially increases the cost of the badges. Another problem with this form of prior art arrangement is that it has been very difficult to encode such clock holes, or marks in such a way that they can be accurately sensed so as to produce only one clock signal corresponding to a given clock hole. The response of most sensors such as are conventionally used for generating such clock signals is such that ringing occurs at both the beginning and the end of the detected clock hole, which ringing may give rise to falsely generated clock signals. Also, the use of clock or reference indicia on the badge itself, while useful in many applications, imposes a requirement that the clock information be very accurately aligned with the encoded data, which is not always the case in practice.